2加根號五的和的2005次方乘二减根號五的差的2005次方加上根號20

2加根號五的和的2005次方乘二减根號五的差的2005次方加上根號20

(2+根號5)^2005 *(2-根號5)^2005 +根號20
=(根號5+2)^2005 * [-(根號5-2)^2005] +根號20
= -(根號5+2)^2005 *(根號5-2)^2005 +根號20
= - [(根號5+2)(根號5-2)]^2005 +根號20
= - [5-4]^2005 +根號20
= -1+根號20
= 2根號5 -1